Friday, June 2, 2017

Science Is Neither 'Settled' Nor 'Skeptical'

Science is increasingly integral to public life. One can hardly avoid taking positions on a range of scientific matters, from climate change, genetically modified foods, genetic testing, and pharmaceuticals, to disease control, patient care, stem cells, and data analytics. Yet most citizens and lawmakers lack the skills or background needed to grasp the underlying technical issues. Scientists are thus guardians of knowledge—however mundane—beyond the reach of average citizens.

This puts the layman in a rather awkward position, for scientists are fickle guardians.

On the one hand, they are fiercely loyal to their knowledge claims. They simply assume that the experimental method is the best way to understand the natural world—and sometimes the only way to understand anything. And they advance their conclusions with a degree of confidence that most other intellectuals can only envy. Thus the layman is reluctant to dismiss or criticize scientific findings, for to do so would require either possessing a similar facility with the scientific method (unlikely) or rejecting that method (unwise).

On the other hand, scientists can be surprisingly disloyal to their knowledge claims, abandoning them as soon as better ones come along. Sometimes they even abandon entire worldviews. The speed of light; the nature of matter; the indivisibility of the atom; the age of the cosmos; the categorizations of the planets; of dinosaurs; the geocentric universe; the clockwork universe—all of these have been or are subject to revision. In science, almost nothing is sacred. Émile Meyerson, the early twentieth-century philosopher of science who influenced Thomas Kuhn, described this situation well:

On the one hand, he sees that scientists demand for their conclusions an authority that is nearly absolute: ... But on the other hand, their pronouncements... clearly display no fixity whatsoever in their eyes... scientists will abandon without scruple an entire system that had, until recently, seemed certain to them. This about face accomplished, they treat as futile ... any attempt to return to the old notions that science and humanity had for a long time seen as infallible expressions of truth—precisely because they obeyed the injunctions of scientists themselves.

The problem is that science is both dogmatic and skeptical—or rather, neither fully dogmatic nor fully skeptical—a bewildering characteristic that allows science to advance. But the disfiguring lenses of popular journalism and political debate transform this healthy tension into an untenable disjunction. On the one hand, we are told: “The science is settled!” Question not. On the other: “Science is never settled!” Question all. Depending on the issue, say, climate change or GMOs, politicians and pundits on the left or right will opportunistically appeal to one or the other.

Purveyors of “settled science” implicitly offer a picture of the scientific community as inviolable dispensers of knowledge. Knowledge here is a product to be consumed by the lay public. Questioning scientific findings, their alleged certitude, or policy implications is thus tantamount to rejecting the product wholesale. Disparaging analogies with “Flat-Earthers,” even Holocaust deniers, follow close behind.

Sensing something awry with such dogmatic invocations and the simplistic image of scientific inquiry they presuppose, some go to the other extreme, radically and skeptically questioning all scientific authority. They maintain “settled science” is a myth. Invocations of Galileo’s audacious pursuit of truth in the face of Church strictures follow close behind. Sometimes such skepticism turns into cynicism about the scientific enterprise itself.

Start with the skeptics. Scientists patently do not question everything: they are not, in general, skeptical about our capacity to gain knowledge about the natural world or about the reliability of the scientific method. Can we trust our senses? Can we be sure that our scientific theories correspond to reality? Do we ever have sufficient justification for our beliefs? Scientists dogmatically assume affirmative answers to these ancient philosophical questions, believing knowledge is possible and that their methods and standards of evidence are sufficient to achieve it. That’s not skepticism; and we are all the better for it—or at any rate, more knowledgeable. For thoroughgoing skepticism, see Sextus Empiricus, not Physics 101.

In fact, few scientists question the central hypotheses of their fields, much less the standards of evidence used to corroborate those hypotheses. As Kuhn observed: the bulk of scientific work consists in filling out the picture of an already accepted paradigm, not re-testing basic assumptions. Most astrophysicists take as given not only that sensory evidence, observational instruments, or experimental testing are reliable, but also that the speed of light is invariant and that spacetime has a pseudo-Riemannian geometric structure. Of course these are not arbitrary assumptions, having been battled tested by past research. The point is that scientists typically do not reinvent the wheel, much less radically question everything; rather, they often accept on faith the soundness of other scientists’ conclusions. And this is a good thing; else, no progress could be made.

As Aristotle pointed out, a valid demonstration must begin with certain premises that cannot be demonstrated. For example, to prove the Pythagorean Theorem, one must accept Euclid’s axioms. Only a skeptic demands a proof of these “first principles.” So too in modern science: the scientist must begin with certain principles. To prove his universal law of gravitation, for example, Newton had to assume Kepler’s laws of planetary motion. Of course, Kepler himself proved his laws; but then he had to assume other laws, and so on. Historically, scientific principles are hard fought on the basis of observation and experiment. But once these principles triumph, as with the ruling class, the textbooks are rewritten so as to ignore their bloody pedigree. They are presented as truths no rational person could doubt: the “dogmas” of the scientific community.

It does not follow that scientists never test hypotheses or question assumptions. Despite periods of relative calm in science, scientists remain epistemological opportunists: once their “dogmas” cease to bear fruit, they abandon them. Scientific revolutions occur precisely when anomalies persist or new theories emerge to better explain the data. But scientists will only accept a new theory for want of a better alternative.

Thus scientific dogmas are never truly dogmatic. History shows that faced with sufficient new evidence or better alternatives, scientists will abandon even the most orthodox principles and theories. The infinite velocity of light; the existence of absolute space; the tri-dimensionality of space; the luminferous aether; classical determinism—all these were once considered “settled;” yet none has reemerged from the dustbin of history. No scientific truth, however robust, is ever immutable.

This fact is hardwired into the nature of empirical science. Empirical reasoning is inductive, advancing from observations to probabilistic generalizations, rather than deductive, moving from universal truths to necessary conclusions. When scientists—or, more often, pundits—express absolute certainty about scientific theories, they go far beyond what any empirical evidence ever warrants. If scientific laws are empirically confirmed, then, no matter how robust, they can be—in principle—empirically disconfirmed. To say otherwise is disingenuous.

So skeptics are right that scientific conclusions should always be open to revision on the basis of empirical evidence. But they are wrong that everything in science is subject to doubt. Scientists deserve leeway in assuming the reliability of their methods—even in accepting some of their findings “dogmatically,” if not immutably. What is required, in other words, is a healthy experimental attitude—equal parts half-hearted dogmatism and half-hearted skepticism—one that Galileo embodied famously and cantankerously.

As for citizens and politicians? They must recognize that science policy making is a messy and drawn-out affair. Scientific knowledge is not a product to be consumed or rejected wholesale, but a process—one in which the layman plays a role. We are obliged thus to respect the authority and methodology of science, while engaging with its conclusions critically, not to say skeptically.

M. Anthony Mills is an associate editor of The New Atlantis and a PhD candidate in philosophy at the University of Notre Dame.